Title: Final Report - "CO2 Sequestration in Cell Biomass of Chlorobium Thiosulfatophilum"

Abstract

World carbon dioxide emissions from the combustion of fossil fuels have increased at a rate of about 3 percent per year during the last 40 years to over 24 billion tons today. While a number of methods have been proposed and are under study for dealing with the carbon dioxide problem, all have advantages as well as disadvantages which limit their application. The anaerobic bacterium Chlorobium thiosulfatophilum uses hydrogen sulfide and carbon dioxide to produce elemental sulfur and cell biomass. The overall objective of this project is to develop a commercial process for the biological sequestration of carbon dioxide and simultaneous conversion of hydrogen sulfide to elemental sulfur. The Phase I study successfully demonstrated the technical feasibility of utilizing this bacterium for carbon dioxide sequestration and hydrogen sulfide conversion to elemental sulfur by utilizing the bacterium in continuous reactor studies. Phase II studies involved an advanced research and development to develop the engineering and scale-up parameters for commercialization of the technology. Tasks include culture isolation and optimization studies, further continuous reactor studies, light delivery systems, high pressure studies, process scale-up, a market analysis and economic projections. A number of anaerobic and aerobic microorgansims, both non-photosynthetic and photosynthetic, were examined tomore » find those with the fastest rates for detailed study to continuous culture experiments. C. thiosulfatophilum was selected for study to anaerobically produce sulfur and Thiomicrospira crunogena waws selected for study to produce sulfate non-photosynthetically. Optimal conditions for growth, H2S and CO2 comparison, supplying light and separating sulfur were defined. The design and economic projections show that light supply for photosynthetic reactions is far too expensive, even when solar systems are considered. However, the aerobic non-photosynthetic reaction to produce sulfate with T. crunogena produces a reasonable return when treating a sour gas stream of 120 million SCFD containing 2.5 percent H2S. In this case, the primary source of revenue is from desulfurization of the gas stream. While the technology has significant application in sequestering carbon dioxide in cell biomass or single cell proten (SCP), perhaps the most immediate application is in desulfurizing LGNG or other gas streams. This biological approach is a viable economical alternative to existing hydrogen sulfide removal technology, and is not sensitive to the presence of hydrocarbons which act as catalyst poisons.« less

Authors:

James L Gaddy, PhD; Ching-Whan Ko, PhD

Publication Date:

Mon May 04 00:00:00 EDT 2009

Research Org.:

Bioengineering Resources, Inc.

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

951892

Report Number(s):

DOE/ER/83907-3
TRN: US200917%%404

DOE Contract Number:  

FG02-04ER83907

Resource Type:

Technical Report

Country of Publication:

United States

Language:

English

Subject:

03 NATURAL GAS; BIOMASS; CARBON DIOXIDE; CATALYSTS; COMBUSTION; COMMERCIALIZATION; CONTINUOUS CULTURE; DESULFURIZATION; ECONOMICS; FOSSIL FUELS; HYDROCARBONS; HYDROGEN SULFIDES; MARKET; OPTIMIZATION; SINGLE CELL PROTEIN; SOLAR SYSTEM; SULFATES; SULFUR; carbon dioxide, hydrogen sulfide, Chlorobium thiosulfatophilum, Thiomicrospira crunogena, sulfur